JavaProgramTo.com: How To Compare Two Dates In Java and New Java 8?

1. Overview

In this article, You'll learn how to compare two dates in java and also how to compare the dates in java 8.

Dates comparison means checking whether the date 1 is after date 2 or which one is older or future date.

First let us look into the older java api in java 7 and next exploring the different options with JDK 8.

If-else condition example

2. Comparing Two Dates

First, Let us create two Date objects in format of "yyyy-MM-dd" using SimpleDateFormat.parse() method.

Next, use compareTo() method to compare the dates. compareTo() method returns integer value.

If the returned value is 0, it means both dates are same.
If the value > 0 then date 1 is after date 2.
if the value < 0 then date 1 is before date 2.

package com.javaprogramto.java8.dates.compare;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * Example program to compare two dates in java
 * 
 * @author JavaProgramTo.com
 *
 */
public class DateCompareBeforeJava8 {

	public static void main(String[] args) throws ParseException {
		// Date format
		String DATE_FORMAT = "yyyy-MM-dd";
		
		// Creating an object for SimpleDateFormat
		SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT);
		
		// Date 1 created from string using SimpleDateFormat
		Date date1 = sdf.parse("2021-01-01");

		// Date 2 created from string using SimpleDateFormat
		Date date2 = sdf.parse("2021-02-01");
		
		// comparing two dates
		int dateOrder = date1.compareTo(date2);
		
		// printing the date comparison value returned by compareTo() method
		System.out.println("Dates comparision value : "+dateOrder);
		
		// Deciding the dates order.
		if(dateOrder == 0) {
			System.out.println("Date 1 and Date 2 are equal.");
		} else if(dateOrder > 0) {
			System.out.println("Date 1 is after Date 2.");
		} else {
			System.out.println("Date 1 before Date 2");
		}
	}
}

Output:

Dates comparision value : -1
Date 1 before Date 2

In the above example code, We called date1.compareTo(date2) and it returned value -1. So, it is indicating date 1 is older than date 2. Finally, it has executed else block.

If you swap the dates the it will say date 1 is after date 2.

3. Java 8 - Comparing Two Dates

Java 8 is added with lots of new features and DateTime api is one them.

There are mainly 3 classes added in java 8 to work with dates.

java.time.LocalDate
java.time.LocalDateTime
java.time.ZonedDateTime

Let us try to compare the same dates using java 8 api first with examples then we will understand when to which one from above three mostly used classes.

package com.javaprogramto.java8.dates.compare;

import java.text.ParseException;
import java.time.LocalDate;

/**
 * Example program to compare two dates in java 8 with LocalDate.
 * 
 * @author JavaProgramTo.com
 *
 */
public class DateCompareInJava8 {

	public static void main(String[] args) throws ParseException {
		
		// Creating first date using LocalDate.of() method.
		LocalDate date1 = LocalDate.of(2021, 01, 01);
		
		// Creating second date using LocalDate.of() method.
		LocalDate date2 = LocalDate.of(2021, 02, 01);
		
		// comparing dates with isEqual(), isAfter() and isBefore() methods.
		boolean isEqual = date1.isEqual(date2);
		boolean isAfter = date1.isAfter(date2);
		boolean isBefore = date1.isBefore(date2);
		
		// java 8 date comparisons results
		System.out.println("Date 1 and Date 2 are equals? : "+isEqual);
		System.out.println("Date 1 is after Date 2? : "+isAfter);
		System.out.println("Date 1 is before Date 2? : "+isBefore);
		

		// comparing two dates older way with compareTo() method.
		int dateOrder = date1.compareTo(date2);
		
		// printing the date comparison value returned by compareTo() method
		System.out.println("Dates comparision value with compareTo() returned value : "+dateOrder);
		
		// Deciding the dates order.
		if(dateOrder == 0) {
			System.out.println("Date 1 and Date 2 are equal.");
		} else if(dateOrder > 0) {
			System.out.println("Date 1 is after Date 2.");
		} else {
			System.out.println("Date 1 before Date 2");
		}

	}

}

Output:

Date 1 and Date 2 are equals? : false
Date 1 is after Date 2? : false
Date 1 is before Date 2? : true
Dates comparision value with compareTo() returned value : -1
Date 1 before Date 2

In the above example, we have used LocaleDate class methods isEqual(), isAfter() and isBefore() methods to compare the dates order.

If these methods returns true means that method condition is satisfied else not met the condition.

And alos still the new api has the compareTo() method to work with the older jdk.

4. Java 8 - Comparing Two Dates Along With Time Component

In java 8, LocalDate class compares only the dates and does not consider time part in the date. Other two classes such as LocalDateTime and ZonedDateTime work with date along with time. All 3 classes have isEqual(), isAfter() and isBefore() methods for dates comparisons.

Now, look at the date and time comparisons examples using LocalDateTime and ZonedDateTime classes.

LocalDateTime Example:

package com.javaprogramto.java8.dates.compare;

import java.text.ParseException;
import java.time.LocalDate;
import java.time.LocalDateTime;

/**
 * Example program to compare two dates in java 8 with LocalDateTime.
 * 
 * @author JavaProgramTo.com
 *
 */
public class DateCompareLocalDateTimeInJava8 {

	public static void main(String[] args) throws ParseException {

		// Creating first date using LocalDateTime.of() method.
		LocalDateTime datetime1 = LocalDateTime.of(2021, 02, 01, 01, 01, 01);

		// Creating second date using LocalDateTime.now() method with milliseconds.
		LocalDateTime datetime2 = LocalDateTime.now();

		// comparing dates with isEqual(), isAfter() and isBefore() methods.
		boolean isEqual = datetime1.isEqual(datetime2);
		boolean isAfter = datetime1.isAfter(datetime2);
		boolean isBefore = datetime1.isBefore(datetime2);

		// java 8 date comparisons results
		System.out.println("DateTime 1 and DateTime 2 are equals? : " + isEqual);
		System.out.println("DateTime 1 is after DateTime 2? : " + isAfter);
		System.out.println("DateTime 1 is before DateTime 2? : " + isBefore);
	}

}

Output:

DateTime 1 and DateTime 2 are equals? : false
DateTime 1 is after DateTime 2? : true
DateTime 1 is before DateTime 2? : false

ZonedDateTime Example:

package com.javaprogramto.java8.dates.compare;

import java.text.ParseException;
import java.time.ZoneId;
import java.time.ZonedDateTime;

/**
 * Example program to compare two dates in java 8 with ZonedDateTime.
 * 
 * @author JavaProgramTo.com
 *
 */
public class DateCompareZonedDateTimeInJava8 {

	public static void main(String[] args) throws ParseException {

		// Creating first date using ZonedDateTime.of() method with nano seconds and time zone id.
		ZonedDateTime zonesDatetime1 = ZonedDateTime.of(2021, 02, 01, 01, 01, 01, 1, ZoneId.systemDefault());

		// Creating second date using ZonedDateTime.now() method with milliseconds.
		ZonedDateTime zonedDatetime2 = ZonedDateTime.now();

		// comparing dates with isEqual(), isAfter() and isBefore() methods.
		boolean isEqual = zonesDatetime1.isEqual(zonedDatetime2);
		boolean isAfter = zonesDatetime1.isAfter(zonedDatetime2);
		boolean isBefore = zonesDatetime1.isBefore(zonedDatetime2);

		// java 8 date comparisons results
		System.out.println("ZonedDateTime 1 and ZonedDateTime 2 are equals? : " + isEqual);
		System.out.println("ZonedDateTime 1 is after ZonedDateTime 2? : " + isAfter);
		System.out.println("ZonedDateTime 1 is before ZonedDateTime 2? : " + isBefore);
	}

}

Output:

ZonedDateTime 1 and ZonedDateTime 2 are equals? : false
ZonedDateTime 1 is after ZonedDateTime 2? : true
ZonedDateTime 1 is before ZonedDateTime 2? : false